csce465pine64backup/hw3/task4/find_key.cpp

#include <cstdio>
#include <iostream>
#include <fstream>
#include <cstring>
#include <ctype.h>
#include <openssl/evp.h>

using namespace std;

int do_crypt(FILE *in, FILE *out, string inkey, int do_encrypt)
{
    /* Allow enough space in output buffer for additional block */
    unsigned char inbuf[1024], outbuf[1024 + EVP_MAX_BLOCK_LENGTH];
    int inlen, outlen;
    EVP_CIPHER_CTX *ctx;
    /*
     * Bogus key and IV: we'd normally set these from
     * another source.
    */
    unsigned char iv[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
    //unsigned char iv[] = "0000000000000000";
    unsigned char key[16];

    for(int i = 0; i < 16; i++)
    {
        if(i < inkey.length())
        {
            key[i] = inkey.at(i);
        }
        else
        {
            key[i] = '\x20';
        }
    }
    //string str( key, key + sizeof key / sizeof key[0] );
    //cout << str << endl;
    /* Don't set key or IV right away; we want to check lengths */
    ctx = EVP_CIPHER_CTX_new();
    EVP_CipherInit_ex(ctx, EVP_aes_128_cbc(), NULL, NULL, NULL, do_encrypt);
    OPENSSL_assert(EVP_CIPHER_CTX_key_length(ctx) == 16);
    OPENSSL_assert(EVP_CIPHER_CTX_iv_length(ctx) == 16);
    /* Now we can set key and IV */
    EVP_CipherInit_ex(ctx, NULL, NULL, key, iv, do_encrypt);
    for (;;) {
        inlen = fread(inbuf, 1, 256, in);
        if (inlen <= 0)
            break;
        if (!EVP_CipherUpdate(ctx, outbuf, &outlen, inbuf, inlen)) {
            /* Error */
            EVP_CIPHER_CTX_free(ctx);
            return 0;
        }
        fwrite(outbuf, 1, outlen, out);
    }
    if (!EVP_CipherFinal_ex(ctx, outbuf, &outlen)) {
        /* Error */
        EVP_CIPHER_CTX_free(ctx);
        return 0;
    }

    cout << "I made it." << endl;
    if(outlen > 0)
        cout << outbuf << endl;
    fwrite(outbuf, 1, outlen, out);

    EVP_CIPHER_CTX_free(ctx);
    return 1;
}

int main()
{
    cout << "Test." << endl;

    FILE *input;
    FILE *output;
    //FILE *original;

    input = fopen("ciphertext.txt", "rb");
    output = fopen("testing.txt", "wb");
    //original = fopen("plaintext.txt", "r");

    ifstream words("words.txt");
    ifstream original("plaintext.txt");

    string key = "0123456789abcdef";
    
    string secret = "";
    getline(original, secret);

    char line[256];

    unsigned char keyc[16];
    
    while(!words.eof())
    {
        key = "";
        getline(words, key);
        if(key.length() > 16)
        {
            continue;
        }
        //cout << key << endl;

        do_crypt(input, output, key, 0);
 
        fclose(output);
        output = fopen("testing.txt", "r");
     
        if (NULL != output)
        {
            fseek (output, 0, SEEK_END);
            int size = ftell(output);
            
            if (0 != size)
            {
                fgets(line, sizeof(line), output);
                cout << key << "\t" << secret << "\t" << line << endl;
            }
        }

        fclose(output);
        output = fopen("testing.txt", "wb");
    }

    fclose(input);
    fclose(output);
    words.close();
    original.close();

    return 0;
}